Door operating mechanism



July 18, 1939. E. R. GREER DOOR OPERATING MECHANISM Filed June 20, 1936 4 Sheets-Sheet 1 July 18, 1939. E. R. GREER DOOR OPERATING MECHANISM Filed June 20, 1936 4 Sheets-Sheet 2 July 18, 1939.. E. R. GREER DOOR OPERATING MECHANISM Filed June 20, 1936 4 Sheets-Sheet 3 4 Sheets-s 4 E. R. GREER DOOR OPERATING MECHANISM Filed June 20, 1936 Patented July 18, 1939 UNITED STATES PATENT OFFICE Allis-Chalmers Manufacturing Company,

Mil-

waukee, Wis., a corporation of Delaware Application June 20,

9 Claims.

The invention relates to dump wagons and is concerned more specifically with a mechanism for operating the doors of such'vehicles, particularly bottom dump doors. Subject matter dis- .closed but not specifically claimed herein is claimed in United States Patent 2,092,309, September '7, 1937, to E. R. Greer and E. F. Norelius, .Door operating mechanism.

In the operation ofa bottom dump wagon it is usually desired that the doors, upon unlocking, .openfreely, that is, practically without restraint, so that'the entire load may dump practically all at once and the doors may strike a stop at the end of their opening movement rather violently in order to jar loose any dirt which may cling to the doors. On the other hand, it has become a preferred practice to close the doors of a dump wagon "by mechanical power after the load has been dumped, and in order to answer both of the mentioned requirements, that is, the requirement of unrestrained opening movement of the doors and the requirement of closing the doors by mechanical power, the following mode of operation has heretofore been suggested. A reciprocable element such as a piston, is suitably connected with a door actuating shaft to impart door closing movement to the shaft by movement of the piston in one direction. After the doors have been closed they are held closed by means other than the piston and the latter is returned toits starting position independently of opening move- .ment of the doors. The return movement of the piston to its starting position while the doors are being held in closed position relieves the doors from the work of restoring the piston to its starting position, and the doors may therefore open substantially without restraint.

It is an object of the invention to provide an improved mechanism of the above mentioned character.

Another object of the invention is to provide a hydraulically actuated door operating mechanism which permits unrestrained opening of the doorsin the mentioned manner, which is simple and compact in construction, and eflicient in operation.

These and other objects and advantages of the invention will be apparent from the following description. A clear conception of an embodiment of the invention and of the operation of a device constructed in accordance therewith, may be had by referring to the drawings accompanying and forming apart of this specification in which like reference characters designate the same or similar parts in the various views:

Fig. 1 is a side view of a cart type bottom dump wagon hitched to a tractor;

Fig, 2 is a detail view of a winding shaft for closing the doors of the bottom dump wagon shown in Fig. 1;

1936, Serial No. 86,276

Fig. 3 is a rear view of the door winding mechanism at the rear of the bottom dump wagon shown in Fig.1;

Fig. 4 is a side view of the mechanism shown .in Fig. 3;

Fig. 5 is a section on line V-V of Fig. 3, showing the mechanism in a position different from the position in which it is shown in Fig. 4;

Fig. 6 is a section on line VI-VI of Fig. 3,

showing the mechanism in the same position in which it is shown in Fig. 5;

Fig. '7 is a diagrammatic view of a hydraulic power system in connection with the winding mechanism shown in Fig, '3; and

Fig. 8 is a partial section on line VIII-VIII of Fig. 1.

The bottom dump wagon shown in Fig. 1 has a substantially rectangular tubular frame 1, on which a hopperlike wagon box '9 is mounted, the rear wall of the wagon box being indicated by ID. A pair of bottom dump doors I are hingedly secured to the longitudinal side portions of the frame -'I by means of suitable hangers generally indicated in Fig. 1 by the reference character 8 and more clearly shown in Fig. 8, Fig. 8 being a section through the lower near side of the wagon, shown in Fig. 1. As shown in Fig. 8, a U-bolt 86 is secured to a plate 81 extending downwardly from the tubular member 88 of the frame I, and a casting 89 secured to the door I has a pair of ears 90 at opposite sides of the U-bolt 86. A pin 9| extending through the ears 90 and through the U-bolt 86 pivotally connects the casting with the U-bolt and therefore the door I with the frame I. Thecasting 89 is also formed with a socket in which a coil spring 92 is seated, the coil spring being wound of square wire and adapted to be compressed between the tubular frame member 88 and the bottom of the socket in the casting. Each door I is hingedly connected to the frame 1 by three hanger arrangements of the type shown in Fig. 8, and it will be seen that if the doors are permitted to swing open without restraint the coil spring 92 will come into contact with the tubular frame member 88 but as the springs are comparatively weak, they will become solid almost instantly and the doors will be stopped in their opening movement very suddenly, producing a jar upon the doors which will shake loose any dirt that may cling to'the doors. The wagon is hitched to a tractor 4, of which only the rear end is shown in Fig. 1, a drivers seat on the tractor being indicated by the reference character 5. The tractor and the wagon are flexibly connected by a universal hitch 6, so that the tractor and the wagon may move relative to each other when the vehicle train is driven through a curve or over rough ground. A winding shaft H is mounted on the wagon box 9 by means of journal bearings l2 and I3 (Fig. 2)

which are secured to the outer side of the rear wall III of the wagon box. The doors I are connected with the winding shaft II through a chain arrangement comprising chain portions 2 secured to the doors and guided over pulleys 3 mounted in the side walls of the wagon box, and chain portions I4 which are connected to the chain portions 2 and secured to sheaves I5 and I6 mounted on the ends of the winding shaft, as shown in Fig. 2. It will be seen that rotation of the winding shaft in clockwise direction, with reference to Fig. 1, will wind up the chain portions I4 on the sheaves I5 and I6 and thereby cause the doors to be closed, and that opening movement of the doors will cause rotation of the shaft I I in anticlockwise direction, with reference to Fig. 1. The mechanism described hereinbelow serves the purpose of winding up the doors by rotation of the shaft II in clockwise direction, and on the other hand permits practically unrestrained rotation of shaft I I in anti-clockwise direction during the opening movement of the doors, so that a load may be dumped from the wagon box all at once and any dirt clinging to the doors will be shaken loose by jar of the doors when they come to a stop at the end of the opening movement.

Mounted on the shaft II by means of bearings 56 is a frame I1, comprising side plates I8 and I9, an angle iron 20 connecting the side plates at their lower ends, and an angle iron 2| connecting the side plates between their upper and lower ends. The bearings 56 are secured to the side plates IB and I9, and the frame I1 is prevented from swinging about the shaft II by a lug 22 which extends laterally from the side plate I9 and is bolted to the wagon box. Mounted on the frame I1 is a hydraulic cylinder 23 which is secured at its lower end to the angle iron in the middle between the side plates I8 and I9. A piston rod 24 extends through the upper end of the hydraulic cylinder and is connected at its lower end to a piston 23' within the cylinder 23. The upper end of the piston rod 24 is connected to a cross head 25 which is guided between the side plates I8 and I9 and between guides 26 and 26' secured to the inner sides of the side plates I8 and I9. A pair of coil springs 21 urge the cross head upwardly and normally hold it in its highest position, that is, in the position in which the piston in the cylinder 23 is at the upper end of its stroke, heads at the upper ends of rods 55 being relied upon as a stop, the rods being adjustably secured at their lower ends to the angle iron 20 and having sliding engagement with the cross head 25. The coil springs are held in place by telescoping tubes 28 and 29, the tubes 28 being secured to the angle iron 20 and the tubes 29 to the cross head 25. A link chain 30 connects the cross head 25 with the winding shaft II, one end of the link chain being secured to the cross head as shown in Fig. 4, and the other end of the chain being secured to a sleeve 3| with suitable fastening ears 32, the sleeve being rigidly secured to the shaft I I, see Fig. 2.

The sheaves I5 and IE on the winding shaft I I have sufiiciently large diameters so that rotation of theshaft through an angle of about 250 in one direction will cause full opening of the doors, and so that rotation of the shaft II through the same anglein the opposite direction will cause complete closing of the doors from their fully open position. In Fig. 6 the sleeve 3| and the fastening ears 32 thereon are shown in the position which they occupy when the doors are fully open; that is, in the position of the sleeve 3| and ears 32, as shown in Fig. 6, the shaft II is in a rotated position in which the chains I4 are unwound from the sheaves I5 and I6 and from which position the shaft I I must be rotated in anti-clockwise direction, with reference to Fig. 6, through an angle of about 250 in order to close the doors completely. Such rotation is imparted to the shaft II through the link chain 30 by a descent of the cross head 25 in the frame I1. In order to cause a downward movement of the cross head, fluid under pressure, preferably oil, is admitted into the cylinder 23 above the piston therein as at 33, and when the piston reaches the lower end of its stroke the sleeve 3| and fastening ears 32 thereon are in the position shown in Fig. 4, which is the position which the sleeve and ears occupy when the doors are completely closed. After the shaft has been rotated through an angle of about 250 in order to close the doors, reverse rotation thereof is prevented by a ratchet gear described more fully hereinbelow, the oil pressure above the piston in the cylinder is released and the cross head returns into its highest position under the pressure of the coil springs 21. Due to the upward movement of the crosshead, while the shaft II is prevented from rotating in door opening direction, the chain 30 slackens and, being subject to the force of gravity, it assumes the form of a loop the lower portion of which rests on a shelf 34 as shown in Fig. 4. The shelf is secured to the cross head 25 in any suitable manner. Instead of letting the slack chain rest on a shelf, as shown, a spring pressed roller may be employed to pull the slack chain away from the shaft II and from the cross head 25 into a position substantially as shown in Fig. 4, the purpose being to prevent the slack chain from becoming entangled in the mechanism.

The ratchet gear for holding the shaft I I against reverse rotation after the doors have been closed, is shown at the right of Fig. 3. It comprises a ratchet wheel 35 which is keyed on the shaft I I, and a pawl 36 supported by a pair of arms 31. The arms 31 are rigidly secured to a long sleeve 38 which is rotatably supported one. pin 39,the pin being mounted at one end in an upward extension of the side plate I8 of the frame I1, and at the other end in a plate 40 pivotally supported on the shaft II and connected at its lower end to the side plate I9 of the frame I1 by a cross plate 4|. The cross plate 4| carries an adjustable stop, in the form of a set screw 42, for the pawl supporting arms 31, the latter being connected at their lower ends 'by a cross piece 43 which engages the end of the set screw 42. A spring 44 connected at one end to the side plate I9 of the frame I1 and at the other end to one of the arms 31, draws the cross piece 43 against the set screw 42. The pawl 36 is pivotally mounted between the arms 31 on a pin 45 and has a depending weighted portion so as to be urged by gravity into engagement with the teeth of the ratchet Wheel 35. The portions of the arms 31 between the pins 39 and 45, the pins and the pawl, constitute a toggle relationship which may be adjusted by the set screw 42.

The ratchet "wheel is unlocked by swinging the arms 31 outwardly, that is, away from the set screw 42. For this purpose the sleeve 38 carries two bell crank levers 46 and 41 which are rigidly secured to the sleeve at opposite sides of a central vertical plane through the cylinder 23. Fig. 4 shows the bell crank lever 41 in the position which it occupies when the cross piece 43 of the downward movement.

pawl supporting arms 31 engages the set screw 42, and in that position the upper arm of the bell crank lever extends substantially horizontally from the sleeve 38 and over the shaft ll, while the lower arm extends downwardly and outwardly towards the wall of the wagon box on which the mechanism is mounted. The other bell crank lever '46 is similarly positioned on the sleeve 38, and the ends of the lower arms of both bell crank levers are connected by an angle iron cross piece 48, one flange of the angle iron extending downwardly and rearwardly as shown in Fig. 6. The upper arms-of the bell cranklevers are connected at their ends by a pin on which two L-shaped trigger arms 49 are pivotally mounted by .means of a sleeve 59, as more clearly shown in Fig. 3. The trigger arms 49 are connected at their lowerends by a cross member 5|, and, near the angle of the L, by a plate like cross member 5'! which is not only a reinforcing element but primarily an abutment which may be struck by the lugs 32 and the chain 36 when the shaft ll rotates in clockwise direction, with reference to Fig. 4, the purpose being to swing the trigger arms 49 from the position in which they are shown in Fig. 4 into the position in which they are shown in Fig. 6. A cross pin 58 extending through the trigger arms 49 near their lower ends projects laterally therefrom and engages the guides 23' to limit swinging movement of the trigger arms about the axis of pin 59 in clockwise direction, with reference to Fig. 4. When the cross pin 58 engages the guides 26 the cross member 5| of the "trigger arms projects into the path of the cross head 25, as shown in Fig. 4 and the upper legs of the trigger arms are kept spaced from the shaft I I so that when the cross head 25 strikes the cross member 5|, the trigger arms may move with the cross head in a downward direction atleast for a limited length of travel. Pivotally secured to another cross pin 59 between the trigger arms 49 is a bolt 53 which extends slidably through the downwardly and rearwardly extending flange of the cross member 48 between the bell crank levers 4-6 and 4'5, and

which carries at its outer end a pair of nuts 69,

one nut serving as a jam nut for the other. The

nut 63 closest to the downwardly and rearwardly extending flange of the cross piece 48 is so adjusted on the bolt 53 as to provide for some clearance between said nut and the flange, while the mechanism is in the position in which it is shown in Fig. 4. When the cross head 25 moves downward in what may be called an advance direction, it strikes the cross member 5| of the trigger arms and pulls downwardly on the trigger arms, causing the bell crank levers 45 and 4'! to pivot on the axis of pin '39. The mentioned clearance between the first nut 69 and the cross piece 48 permits limited pivotal movement -,of the bell crank levers while the cross member 5| remains engaged with the cross head .25. The limited pivotal movement of the bell .crank levers about the axis of pin39 is transmitted through the tube .38 to the pawl carrying arms 3'!, causing the pawl 36 to kick over center and consequent release of the ratchet wheel 35. Under the weight of the doors I and the load resting thereon, if the wagon is loaded, the shaft will then spin around rapidly in clockwise-direction, with reference to Fig. 4, and the lugs 32 willstrike against the abutment 51, causing the cross member 5! to be pulled out of engagement with the cross head 25 and thus clearing the path of the latter for continued A tubular spacer 6| (Fig.

6) and :a light compression coil spring 52 are arranged on the bolt 53 in the space between the downwardly and .rearwardly extending flange of the cross piece 48 and the cross pin 59. When the cross member 51 on the trigger arms is struck by the lugs 32 the ensuing movement of the trigger arms first compresses the coil spring 52 and then positively pushes the bell crank levers 46 and '41 about the axis of pin 39 in anti-clockwise direction with reference to Fig. 4, due to contact of the tubular spacer 6| with the downwardly .and rearwardly extending flange of the cross piece 48. The positive movement of the bell crank levers 45 and 41 by the tubular spacer 6| causes the pawl 36 to be moved still further away from the ratchet wheel 35, as shown in Fig. 5. The cross member 51 rides on the chain 30 and the pawl will therefore remain in the position relative to the ratchet wheel 35 as shown in Fig. 5 until the shaft H is rotated in anti-clockwise direction, with reference to Fig. 6, far enough to permit the trigger arms 49 to fall back into the position shown in Fig. 4, where the pin 58 engages the guides 26; the pawl 36 will then again be in the-position relative to the ratchet wheel 35, in

which it is shown in Fig. 4.

Referring to Fig. 7, a fluid reservoir is indicated by 52, the reservoir being mounted on the tractor as shown in Fig. 1. Mounted within the reservoir 62 is a pump having a drive shaft with a belt pulley -64 secured thereto at the outside of the reservoir. A belt 65 trained over the pulley 64 is driven by a constantly revolving shaft 66 on the tractor, as generally indicated in Fig. 1.

The pump 63 has an intake opening 61 in communication with the interior of the reservoir 62, and a discharge opening 58 in communication with a conduit 69 leading out of the reservoir. The conduit 69 is connected through a hose 10 with the inlet opening ll of a control valve generally indicated by 12. The valve has two outlet openings, an upper one 13 which communicates with the reservoir 62 through a conduit 14, and a lower one l5 which communicates with the cylinder 23 through a conduit 16. the valve 72 is divided bya partition 11 into two compartments, a left one in communication with the inlet opening TI, and a right one in communication with the outlet opening 13. Com- The body of munication between the right and the left com- 450 partment is controlled by a cylinder element 18 which is rotatable in the valve body andwhich communicates at its left open end with the left compartment of the valve body. Rotation of the cylinder 18 by means of the handle 19 brings an r55 when the handle is rotated into another extreme 560 position the opening BI is fully closed. An opening 82 in the partition l! is normally closed by a spring pressed plunger 83, but upon excessive pressure in the left compartment the plunger 33 permits escape of fluid from the left to the right compartment through the opening 82. The left compartment communicates directly with the outlet opening 15 of the valve body, as shown in Fig. 7. A gate valve 85 is arranged in the conduit l6, and by closing the gate valve 85, the hydraulic cylinder 23 may be put out of commission, if desired.

Theoperation of the mechanism is as follows: Assuming that the mechanism is in the position shown in Fig. 4, the chains l4 are wound up on .75

the sheaves l and I6, and the doors are closed, as stated hereinbefore; the cross piece 43 of the pawl supporting arms 31 engages the set screw 42, andthe pawl 36 engages the ratchet wheel 35, preventing the latter from turning under the torque which acts upon the shaft through the chains 4, the chains being under tension due to the weight of the doors and due to the load of material thereon if the wagon box is loaded. The ratchet gear constitutes the only means for holding the doors closed, there being no other locks or latches for holding the doors closed. When the wagon arrives at the dump the operator, without stopping the vehicle, turns the handle 19 of the valve 12 into the extreme position in which the opening 8| is fully closed, and the entire fluid discharge of the pump 63 will then be forced into the cylinder 23 above the piston therein, as will be clear from Fig. 7. Under the fluid pressure acting upon the piston the cross head 25 begins to descend and strikes the cross member 5| of the trigger arms 49, as will be apparent from Fig. 4. As the cross head continues its downward movement, downward pull is exerted upon the trigger arms 49, and as a result the bell crank levers 46 and 41 will be rotated about the axis of pin 39. The rotation of the bell crank levers is transmitted to the pawl supporting arms 31 through the sleeve 38, and the arms 31 are swung outwardly and carry the pawl supporting pin 45 over the center of the toggle, at which moment the pawl kicks over and the doors fly open, causing the shaft II and ratchet wheel 35 to spin around at great speed, in clockwise direction with reference to Fig. 4. The downward movement of the cross head 25 up to the moment when the doors fly open is comparatively short, and when the pawl 36 kicks over most of the chain 30 is still slack. The ensuing rapid rotation of shaft II and sleeve 3|, however, winds up most of the chain 3|, and atthe moment the doors reach their fully open position there will still be some slack in the chain 3|. As the cross head 25 continues its downward movement it takes up this remaining slack, and while this is being done the doors remain fully open for a short time during which the entire load drops out of the wagon box and the vehicle is drawn clear of the pile of material which has been dumped. Depending on the rapidity with which the pressure fluid is forced into the cylinder 23 more or less time is required to take up the remaining slack of the chain 30, and more or less time will be afforded for drawing the vehicle clear of the pile of material which has been dumped. The present tendency in dirt moving operations is towards high speeds; the wagons are drawn by high speed tractors, and as the wagons do not stop or even slow down for dumping, very little time is necessary to clear the dumped load. Consequently, in the present mechanism the chain 30 may almost become tight when it is wound up on the sleeve 20 by the rotation of shaft after the cross head 25 has struck the cross member 5|. At any rate, the continued downward movement of the cross head 25 will eventually exert a heavy pull on the chain 30, and under this pull the doors will be closed as has been explained hereinbefore. During the last part of the downward movement of the cross head 25 the bell crank levers 46 and 41 return into their normal position which is shown in Fig. 4, as has been explained hereinbefore, the pawl 35 is moved against the ratchet wheel 25, and during the last part of the closing movement of the doors the pawl rides over the teeth of the ratchet wheel. When the piston in cylinder 23 has reached the lower end of its stroke rotation of shaft stops, and the pawl locks the doors in closed position. It is then necessary to release the. pressure of the fluid above the piston 23' in cylinder 23 to permit the springs 21 to return the cross head into its highest position as shown in Fig. 4. In order to release the fluid pressure above piston 23 the operator turns the handle 19 of the valve 12 into the extreme position in which the opening 8| is fully open. The entire fluid above piston 23 is then returned into the reservoir under the action of springs 21, there being practically no pressure set up by the pump because its discharge is then directly connected with the reservoir through the open passage 8|. During its return or upward movement the cross head 25 strikes the cross member 5| again, but this time nothing happens except that the cross member 5| is forced out of the way of the cross head against the pressure of spring 52, the cross member 5| sliding back under the cross head 25 as soon as it has been cleared by the latter.

While the piston in the cylinder 23 moves down under fluid pressure, air is forced out of the cylinder from below the piston through a vent 54, and while the piston moves up under the action of springs 21, air is drawn into the cylinder through said vent.

If it is desired to hold the doors open for a longer time than is afforded by the automatic functioning of the mechanism, this may easily be done by rotating the handle 19 from the extreme position in which the passage 8| is fully closed into the other extreme position in which the passage 8| is fully open as soon as the ratchet gear has been tripped by the initial downward movement of the cross head 25, and before the cross head begins to rotate the shaft by pulling on the chain 30. Due to the opening of passage 8| the cross head will return to its highest position, and if it is later desired to close the doors, the passage 8| is again closed and kept closed long enough to force enough fluid into the cylinder 23 to bring the piston 23 down to the lower end of its stroke. The first part of the downward movement of the cross head up to the time when rotation of the shaft II is started by pull on the chain 30, may be termed an idling movement of the mechanism, and the part of the downward movement of the cross head which causes rotation of the shaft H by pull on the chain 30, may be termed its power movement.

It should be understood that it is not intended to limit the invention to the exact details of construction herein described, for various modifications within the scope of the claims may occur to persons skilled in the art.

What I claim is:

1. In a dump wagon, a door actuating shaft rotatably mounted on the wagon, a frame comprising relatively spaced side members suspended on said shaft and connected by a cross member, a cylinder mounted on said cross member, a piston within said cylinder, a piston rod secured to said piston, a cross head secured to said piston rod, guides for said cross head formed on said side members, coil springs mounted on said cross member and bearing against said cross head, and flexible connecting means between said shaft and cross head, adapted to be wound around said shaft by door opening rotation thereof.

2. A door operating mechanism comprising a horizontally disposed shaft rotatable in door opening and door closing directions, means for controlling door opening rotation of said shaft, a reciprocable element mounted for movement in an upward direction towards said shaft and in a downward direction away from said shaft, a flexible element connected at one end with said shaft and at the other end with said reciprocable element, means for selectively actuating said reciprocable element in said upward and downward directions, upward movement of said reciprocable element, after door closing rtation of said shaft and prior to door opening rotation thereof, causing a portion of said flexible element to become slack, and door opening rotation of said shaft, after said slackening upward movement of said reciprocable element, causing said slack portion of said flexible element to be wound around said shaft, and a shelf member secured to said reciprocable element adjacent to the connection of said flexible element therewith providing a support for the slackened portion of said flexible element.

3. In a vehicle, a body having dump doors, a shaft for operating said doors rotatable in door opening and door closing directions, bearings for said shaft mounted on said body, a frame mounted on said shaft for pivotal movement relative to said body about the axis of said shaft, means associated with said frame reacting upon said body to prevent said frame from rotation about the axis of said shaft in the direction of door opening rotation of said shaft, a flexible element connected with said shaft and adapted to be wound upon said shaft by door opening rotation thereof, and a power actuated element mounted on said frame and connected with said flexible element for exerting pull thereon when wound upon said shaft so as to rotate said shaft in door closing direction.

4. In a vehicle, a body having dump doors, a shaft for operating said doors rotatable in door opening and door closing directions, bearings for said shaft mounted on said body, a frame mounted on said shaft for pivotal movement relative to said body about the axis of said shaft, means associated with said frame reacting upon said body to prevent said frame from rotation about the axis of said shaft in the direction of door opening rotation of said shaft, releasable coupling means between said frame and shaft adapted to prevent rotation of said shaft relative to said frame in door opening direction, a flexible element connected with said shaft and adapted to be wound upon said shaft by door opening rotation thereof, and a power actuated element mounted on said frame and connected with said flexible element for exerting pull thereon when wound upon said shaft so as to rotate said shaft in door closing direction.

5. In a vehicle, a body having dump doors, a shaft for operating said doors rotatable in door opening and door closing directions, bearings for said shaft mounted on said body, a frame mounted on said shaft for pivotal movement relative to said body about the axis of said shaft, means associated with said frame reacting upon said body to prevent said frame from rotation about the axis of said shaft in the direction of door opening rotation of said shaft, pawl means on said frame cooperating with ratchet means on said shaft to hold said shaft against door opening rotation while said doors are closed, said pawl means being releasable to permit rotation of said shaft in door opening direction, a flexible element connected with said shaft and adapted to be wound upon said shaft by door opening rotation thereof, a cylinder supported by said frame, and a piston within said cylinder connected with said flexible element and 0perable by fluid pressure within said cylinder to exert pull on said flexible element when wound upon said shaft so as to rotate said shaft in door closing direction.

6. In a vehicle, a body having dump doors, a rotatable shaft for operating said doors extending along a wall of said body, a frame having pivotal connection with said shaft, bearing means for said shaft, independent of said frame, secured to said body and adapted to retain said shaft and adjacent portions of said frame transversely spaced from said wall, power actuated mechanism on said frame operatively connected with said shaft to rotate said shaft in one direction, and means associated with said frame reacting upon said body to prevent rotation of said frame about said shaft in a direction opposite to the direction in which said shaft is rotated by said power actuated mechanism.

'7. In a vehicle, a body having dump doors, a rotatable shaft for operating said doors extending along a Wall of said body, a frame having pivotal connection with said shaft, a pair of axially spaced journal bearings for said shaft, independent of said frame, secured to said body and retaining said shaft and adjacent portions of said frame transversely spaced from said wall, power actuated mechanism on said frame operatively connected with said shaft to rotate said shaft in one direction, and an abutment on said frame reacting upon said body to prevent rotation of said frame about said shaft in a direction opposite to the direction in which said shaft is rotated by said power actuated mechanism.

8. In a vehicle, a body having dump doors, a rotatable shaft for operating said doors and a lineal support, extending along one of the walls of said body, pivotal connecting means between said shaft and support, journal bearings for said shaft secured to said body, an element mounted on said support for reciprocating movement longitudinally thereof and operatively connected with said shaft for rotating said shaft by movement of said element in one direction, and an abutment on said support spaced from said shaft in the direction of said wall and reacting upon said body to prevent rotation of said support about said shaft in a direction opposite to the direction in which said shaft is rotated by said shaft rotating movement of said reciprocable element.

9. In a vehicle, a body having dump doors, a rotatable shaft for operating said doors and a lineal support extending in substantial right angle relation to each other along one of the walls of said body, pivotal connecting means between said shaft and support, journal bearings for said shaft secured to said body, an element mounted on said support for reciprocating movement longitudinally thereof and operatively connected with said shaft for rotating said shaft by movement of said element in one direction, an abutment on said support spaced from said shaft in the longitudinal direction of said support and reacting upon said body to prevent rotation of said support about said shaft in a direction opposite to the direction in which said shaft is rotated by said shaft rotating movement of said reciprocable element.

EDWARD R. GREER. 

